AGRICULTURE ROOM
RECENT IDEVIELOIPMENTS IN nit CHEMICAL
UTILIZATION Of WOOD
April 1940
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SCHOOL OF FORESTRY
OREGON STATE COLLEG
CORVALLIS, OREGON
UNITED STATES DEPARTMENT OF AGRICULTURE
LFOREST SERVICE
LFOREST PRODUCTS LABORATORY
Madison, Wisconsin
In Cooperation with the University of Wisconsin
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RECENT DEVELOPMENTS IN TEE CHEMICAL UTILIZATION OF WOODBy
C. P. WINSLOW, Director
The southern farmer has a big stake in the harvesting of tree crops -just as he has in taking from the land crops of potatoes, corn, peanuts,
cotton or tobacco. In the South, as elsewhere, the largest farm crop in
acreage is timber; and timber ranks among the first four southern crops in
point of annual dollar value. The development and holding of markets for
farm timber is something neither the farmer nor the extension worker can
deal with unaided. The market for lumber (which, exclusive of fuelwood
constitutes,, 70 percent of all forest products cut) has been declining for
over 30 years. To extend the marketing and utilization of farm timber we
must look to research aimed to find uses for wastes, to improve practices,
and to develop new and useful products.
Because of the existing character of farm timber, chemical research
must play an increasingly important role in developing its industrial uses.
It is perhaps worthwhile also to note in passing that file construction
constitutes the present major use for wood, and there is no present justification for minimizing this field, the use of cellulose products is increasing_by 200,000 tons per year, and-well in the van of industries that
have expanded in the very teeth of depression are the chemical and plastic
industries. My assignment on this program calls for a report on recent
developments in the field of chemical utilization of wood by the Forest
Products Laboratory.
Pulpwood Variability a Guide to Future Diversification
Before mentioning specific new chemical products and processes let
me say a few words about southern pine pulpwood.
Certain phases of the research at the Forest Products Laboratory
apply to pulpwood and pulping. For example :, the influence of conditions
of growth on pulpwood properties is being examined, and studies of the harvesting and marketing of pul pwood are in progress, particularly with
southern species. Some very interesting data relating to pulpwood properties and their influence in the production of pulp has been recently
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-Delivered at the Texas Farm Chemurgic Conference, North Texas State
Teachers College, Denton, Texas, April 26, 1940.
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developed. As you are probably aware there are inherent physical differences in different batches of pulpwood ,-.variations in diameter, rate
of growth, springwood and summerwood, heartwood and sapwood, knots, crook,
and other attributes.
So long as the kraft industry was a sole performer in the southern
pulp field there was little reason to take note of the variability -- or
perhaps we should say the versatility -- of southern pine pulpwood along
lines other than species. With the present tendency toward the development
of bleached sulfate, sulfite, and newsprint in the South, however, the
versatility of southern pine pulpwood takes on new significance.
Without going into the physical differences in springwood and summerwood fibers which dictate such selection, it is possible to say that material of high springwood content will find its best use in the manufacture
of printing and wrapping grades requiring good formation and smooth surface,
accompanied by high bursting and tensile strength. High summerwood conte4t material is better adapted to bulkier papers, such as bagging, boards,
etc., or in papers where tearing strength is important.
The essential differences in the pulping characteristics of heartwood and sapwood suggest another basis for the segregation of material.
Wood which has a large amount of heartwood would necessarily have to go
into kraft, but material running low in this dark-colored and sometimes
pitchy wood might be properly diverted to bleachable sulfate, light-colored
groundwood, or sulfite.
Variability in springwood-summerwood and heartwood-sapwood proportions as affected by height in the tree also opens up possibilities of
diversification as between slow-grown wood or butt bolts and young rapidgrown material or bolts from upper portions of the tree.
With increased diversification of the pulping industry, efficient
industrial operation, as well as sound conservation, , demand that the
inherent variations in pulpwood be used to separate and guide both woods
production and wood incoming to the mill to the uses to which it is best
fitted. The pine trees now growing on southern woodlands and the pulpwood
now being handled constitute a source of raw material from which can be
made all of the different types of paper used in the United States. I believe this important fact justifies such consideration as we have just
given to pulpwood properties and uses
The most important developments in the chemical utilization of wood,
so far as the Forest Products Laboratory is concerned, include some items
which are just coming into important commercial production and other items
which are still in small-scale laboratory experimentation.
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Southern Newsprint From Pine and Gum
As early as 1927, the Laboratory worked out methods for the production
of newsprint paper from various combinations of pine sulfite pulp with pine
or black gum groundwood. From the standpoint of the forests, however, the
sulfite process was undesirable since only the young heart-free pine could
be used.
Later the use of bleached sulfate kraft pulp was developed by the
Forest Products Laboratory to permit the use of pine of any age. It is this
latter process, using a combination of semibleached sulfate pine with pine
groundwood, which is being used in the South's first newsprint mill which
began operations at Lufkin a few months ago.
As just mentioned, it was also shown how black gum groundwood pulp
can be mixed with pine groundwood pulp for the groundwood constituent which
makes up 75 to SO percent of newsprint paper.
Very recently, the Laboratory has further shown how the black and
red gums having light-colored heartwood can be cooked by the Laboratory's
"semichemical" process to p roduce a pulp to replace the much more costly
semibleached kraft pulp for the chemical pulp constituent which makes up
20 to 25 percent of newsprint.
The semichemical process, which consists essentially in a partial
cooking with a reduced amount of chemical followed by mechanical disintegration, gives a 75 percent pulp yield at a cost about the same as for groundwood pulp. With the southern gums, the Laboratory has produced pulps which
mixed in a 1 to 4 ratio with southern pine groundwood made a newsprint
paper equal to commercial grades.
This is of two-fold significance. First, owing to its higher yield,
the cost of semichemical pulp should be no greater than for groundwood and
appreciably lower than that of either sulfite or semibleached kraft pulps.
Secondly, gum is one of the most abundant of the southern hardwoods, which
as a group occupy half of the southern forest.
Blackjack oak and red gum for "corrugating" container board
The semichemical process was develo ped at the Forest Products Laboratory about 15 years ago to produce "corrugating" board, as well as "liner"
for shipping containers from waste extracted chestnut chips in the tannin
industry. Today, 100,000 tons of such board are produced annually from
extracted chestnut. The chestnut supply, however, will ultimately be.exhausted because all of the chestnut trees have been killed by the blight.
Very recently the Laboratory has shown how to use blackjack oak, and red gum
by the same process and has produced container board of quality superior
to that from extracted chestnut.
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Development of Bleached Papers from Southern Woods
Around 1910 there was practically no pulp production in the South.
The Laboratory showed how satisfactory brown kraft pulp for wrapping paper
could be made from southern pines, and upon this work as a basis the great
kraft pulp industry was initiated.
One weakness of this southern industry was that it was restricted
to one type of product -- brown kraft pulp. Laboratory methods were initiated for the development of cooking and bleaching procedure to p roduce a
white pulp. This work had much to do with the present development of
bleached pulps and papers in this region. Incidentally, the use of southern gums and other hardwoods was proved entirely feasible for book and
similar bleached grades of paper.
Pulp and Chemical Products from Wood by Hydrogenation
Recently, by subjecting wood chi p s in water to the action of alkali
and hydrogen with a nickel catalyst at high pressures, it was found that
the hemicellulose and ligtin, which constitute together 50 to Go percent
of wood substance, were converted into a variety of alcohols, oils, and
an alkali-soluble resin, and at the same time the cellulose was recovered
in the form of a pulp. The alcohols include methyl and propyl alcohol and
the previously unknown products of this operation include a hard, glassy,
amber-colored resin that may prove useful - for plastics and lacquers and
several derivatives of propyl cyclohexane, some of which are thick viscous
oils and others thin and toxic in nature.
The pulp has normal fiber length, average alpha cellulose content,
is bleachable, and can be beaten to develop satisfactory sheet-making
properties.
While this new discovery has as yet been applied only on a smallscale laboratory basis and is chiefly of immediate scientific interest, it
holds forth most interesting industrial potentialities.
Low-cost Plastic from Poor-quality and Waste Wood
About 50 percent of the southern forests are in hardwoods with many
species and many defective trees that won t t pay their way when manufactured
into standard lumber and which should be harvested to make room for a new
crop of timber of desirable species; also the aggregate of logging, sawmill, and manufacturing wastes amounts to something like 50 percent of the
tree.
In this connection it is possible to report a process by which a
high-utility low-cost plastic can be produced from Poor-quality and waste
wood. As this plastic has been described to other -d am Chemurgic meetings,
I will ask those who have heard the story to bear with me briefly.
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The essentials of the process are simple. Sawdust or wood chips are
ithydrolyzed" by heating with dilute sulfuric acid, certain resulting sugars
are washed out of the fibrous mass that is left, and this product is dried,
ground fine and mixed with a small amount of aniline and furfural. The
result is a molding powder, which when pressed at 150 0 C. under 3,000 to
4,000 pounds per square inch pressure for a few minutes, becomes a dense, impervious sheet material that offers wide possibilities for use as a floor
tile, switchboard panels, and a variety of other pressed and molded products.
The powder ready for molding should not cost more than 2 to 3 cents per
pound as compared to about 16 cents for the well-known phenolic plastic.
The finished material, which is normally opaque black, receives a
high polish in the mold and its appearance may be altered by the use of
paint, enamel, metallic powders, or decorative overlays of paper, cloth, or
figured veneers.
Commercial production of this plastic is in exploratory stages in
the hands of several large companies and one factory, using low-quality wood,
is now making the molding powder in pilot-plant quantities for trial by
responsible manufacturers.
Another pleasing development is the discovery that hydrolyzed wood
(that is sawdust or chips partially processed in the plastic process) makes
an excellent filler for use in the production of phenolic resins. Plastics
of this type have a greater flow with hydrolyzed wood than with wood-flour
filler and a greater moisture resistance, 25 to 30 percent more hydrolyzed
wood than wood flour can .be used, and it is estimated that by this means a
saving of 1 to 2 cents per pound can be effected in the production of a
filled bakelite molding product.
Let me point out again the possible application of the plastic process
to a wide range of low-grade woodland species and defective timber. Experiments have so far been confined largely to a few hardwoods and the process
has developed in such a way as to accommodate the properties of these species.
There is no present reason to believe that the process could not be extended to a wide range of hardwoods and further modified for conversion of
softwood species. It appears from preliminary experiments that Ozark blackjack oak, which is perhaps the archetype of neglected species crying for
markets in a de pressed rural region, promises to be adaptable to the process.
Chemical Plasticization of Wood and Hogged Waste
It appears that even cheaper plastics from low-quality woods may be
in the offing. Very recently the Laboratory has found that green swamp oak
and blackjack oak, after soaking in a water solution of a single chemical
and drying, becomes thermoplastic. The swamp oak while hot and dry has
been bent and twisted to very sharp curvatures which are retained on cooling;
further, the hot material has been pressed into dense molded or flat shapes
with several pieces in the press fusing together into a solid mass. These
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are true plastic characteristics. The fact that the bent material can be
recurved or straightened on reheating may be altered by later developments
or it may prove advantageous in possible use of the material.
Although financial limitations have permitted this process to be
tried with small-sized hogged material or sawdust only on blackjack oak, a
sawdust plastic has been made from this species and it is reasonable to
expect that it will work with some other species and with hogged wood or
sawdust as well as with boards. This process would be simple and cheap; it
offers a possibility of a plastic of even lower cost, and probably somewhat
different properties than the one produced from hydrolyzed wood. Its development would be of the utmost significance to southern hardwood utilization.
High Alpha Cellulose Yield from Holocellulose
Any development which tends to diversify the demand for southern
pulpwoods reacts to the general good of the southern woodlands. Of interest
in this connection is tha, discovery that wood contains about 50 percent of
alpha cellulose having high-viscosity characteristics similar tQ cotton
instead of the 3E5 percent obtained by the usual pulping processes. Alpha
cellulose is required for the production of rayon and similar cellulosic
products calling for cellulose that has not been degraded in pulping. The
higher fraction recently obtained experimentally -- which was less degraded
than alpha cellulose obtained from the ordinary run of pulps -- was derived
from holocellulose. The problem now is to modify the method to reduce
costs of preparing the 50 percent of alpha cellulose which we know definitely can be realized from this procedure.
Other Accomplishments Affecting Farm Timber Utilization
Research at the Forest Products Laboratory is not, of course, confined to chemical investigations. So far as the utilization of southern
farm woodland timber is concerned there are numerous other activities of
equal significance.
Logging cost and value studies have shown that, for lumber, it is
unprofitable to cut trees below certain,diameter limits, and it is also
bad for the development of the future forest. These findings form the
basis for "selective logging" practice, now increasingly being applied to
southern forest lands as well as elsewhere.
Principles have been developed for log grades, and for similar
pulpwood grades, to the end that the timber owner and particularly the
farm woodland owner can pro p erly select and grade his trees and logs so
that they can be more advantageously sold.
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A truly portable band sawmill (still in the experimental stages) is
under development. It can be moved and operated by a tractor, will not
require costly "resetup" expense, and will cut even thickness boards without
the loss resulting from the wasteful circular saw.
It has been recognized for years that the develo pment of uses for
many of the so-called little-used hardwood species in the southern forest
has been greatly handicapped by lack of information on the machinability of
these woods. Work on the turning, planing, and shaping of 24 southern
species has shown that good results can be obtained if the wood is at the
right moisture content and if the speeds, feeds, and cutting angles of the
machines are properly controlled toaccommodate the species being used.
Glued, laminated structural beams and arches have been developed to
make large structural members from cheap, low-grade, small-sized boards.
The laminated arch has recently been used in 200 buildings which otherwise
would have used some other material.
Engineering data has been worked out for the use of metal connectors
to increase the strength of joints in wooden construction. As a result of
this new construction method, since 1933 there have been 18,000 structures
put up with these fittings in 44 states, and using over 563,000,000 feet of
lumber valued at more than $11,000,000. More than half of this lumber was
from the South.
A system of low-cost prefabricated house construction has been developed, using plywood glued to light framing for the construction of unit
panels for walls, floors, roofs, and other members. The engineering
features have proved sound and the unit panels well adapted to factory
construction. Four companies are now using the main principles, and one
of them has sold so far about 1,000 houses.
I mportance and Present Status of Research on Farm Timber Use
The market needs of the farm woodlands will be especially acute
during the transition period between past neglect and the period of thrifty
and skilled woodland management. Also, the farm group will be especially
affected by any shrinkage of forest products consumption. Standing in the
way of woodland improvement is a vast acreage of timber of low-utility
species and knotty and malformed character that must be thinned out or in
many cases removed once and for all to build up timber production on farm
woodlands. A general program of farm forestry improvement cannot be advanced without sound economic incentives to marketing of the thinnings and
of the accumulation of low-quality timber that has resulted from past
neglect. In view of the present ailing condition of agriculture there is
no phase of timber utilization more deserving of attention that that devoted to developing uses for farm timber.
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The present scope of Federal research in the farm woodland utilization field is entirely inadequate in relation to the magnitude and importance of the problems involved. This becomes evident on examination of
similar work on other crops, for example research to extend the use of
farm products other than wood. The Federal government is spending over
20 million dollars a year on food-crop research, and is now building four
new laboratories to develop new scientific and technical uses for farm
products and byproducts at a cost of from 3 to 4 million dollars annually.
In contrast to this, for research on utilization of the tree crop, which
occupies more land than all farm food crops put together, there is set
aside the sum of only $664,00o. This sum covers all types of forest products research, chemical, research receiving only its proportionate share.
I believe that the research accomplishments I have cited indicate
that forest products research, if properly encouraged, can measure up to
its present obligations and to the opportunities for serving pressing
economic needs that lie ahead.
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